The present technology relates to a receiving circuit, a receiving device, and a receiving method. Specifically, the present technology relates to a receiving circuit, a receiving device, and a receiving method of receiving a positioning signal from a satellite.
Global Navigation Satellite System (GNSS) is known as a system that receives radio waves from a plurality of satellites and determines a position and a speed of a receiver. The GNSS is represented by Global Positioning System (GPS) operated by the United States. Besides the GPS, various other types of systems have been developed and operated. Examples of other types may include COMPASS developed by China, and GLONASS (GLObal NAvigation Satellite System) operated by Russia. Although these systems are different in terms of specification such as a frequency band to be used, these systems adopt a common positioning principle of calculating the position of a receiver based on a distance from each of a plurality of satellites to the receiver.
In order to perform high-precision positioning based on this positioning principle, at least four visible satellites (navigation satellites in an open range in the air) are necessary to determine four unknown numbers including three-dimensional coordinates (x, y, z) of a receiver and an error in a clock. However, in urban areas with many obstacles that block radio waves, the number of visible satellites may be small. Therefore, there has been proposed a receiving device in which a positioning signal from a satellite in the GPS and a positioning signal from a satellite in a system other than the GPS (such as the GLONASS) are simultaneously received by a single antenna (for example, see Japanese Unexamined Patent Application Publication No. 2009-92473).
This receiving device includes two circuits each configured of a mixer, a filter, an amplifier, and the like, and receives signals in different frequency bands with the respective circuits. With this, the receiving device is allowed to receive a plurality of signals in different frequency bands. By being configured to receive signals in a plurality of frequency bands, the receiver is allowed to have the larger number of visible satellites than that in a case where a signal in only one frequency band is received. As a result, positioning accuracy improves.
In addition, the receiving device thus performing the positioning is more convenient when it is smaller, and therefore it is expected to reduce the circuit scale of the receiving device. Moreover, it is necessary to receive positioning signals continuously to measure the position by following the movement of the receiving device, and therefore it is expected to reduce power consumption.